diff --git a/.travis.yml b/.travis.yml
index e6f816a..7ff137e 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -5,6 +5,7 @@ language: php
 php:
   - 7.1
   - 7.2
+  - 7.3
 
 install:
   - composer install
@@ -20,4 +21,4 @@ script:
   - vendor/bin/phpunit --coverage-clover=coverage.xml
 
 after_success:
-    - bash <(curl -s https://codecov.io/bash) -t 284c5fc4-2109-4bb3-822f-82026d67b1bd
\ No newline at end of file
+    - bash <(curl -s https://codecov.io/bash) -t 284c5fc4-2109-4bb3-822f-82026d67b1bd
diff --git a/composer.json b/composer.json
index b7787a2..3daaf81 100644
--- a/composer.json
+++ b/composer.json
@@ -23,9 +23,9 @@
         }
     },
     "require": {
-        "web3p/rlp": "~0.2.1",
-        "web3p/ethereum-util": "~0.1.1",
+        "web3p/rlp": "0.3.2",
+        "web3p/ethereum-util": "~0.1.2",
         "kornrunner/keccak": "~1",
-        "simplito/elliptic-php": "1.0.*"
+        "simplito/elliptic-php": "~1.0.6"
     }
 }
diff --git a/composer.lock b/composer.lock
index 5a0ad5d..9249fb7 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "b4f99eafb5be92c13f45102e918ab6eb",
+    "content-hash": "de28da405ac699ffb57506b1f832536f",
     "packages": [
         {
             "name": "kornrunner/keccak",
@@ -128,16 +128,16 @@
         },
         {
             "name": "simplito/elliptic-php",
-            "version": "1.0.3",
+            "version": "1.0.6",
             "source": {
                 "type": "git",
                 "url": "https://github.com/simplito/elliptic-php.git",
-                "reference": "cab829d270dfd6acdff8383d862ed02a12d1f9dd"
+                "reference": "15652609aa55968d56685c2a9120535ccdc00fd9"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/simplito/elliptic-php/zipball/cab829d270dfd6acdff8383d862ed02a12d1f9dd",
-                "reference": "cab829d270dfd6acdff8383d862ed02a12d1f9dd",
+                "url": "https://api.github.com/repos/simplito/elliptic-php/zipball/15652609aa55968d56685c2a9120535ccdc00fd9",
+                "reference": "15652609aa55968d56685c2a9120535ccdc00fd9",
                 "shasum": ""
             },
             "require": {
@@ -184,20 +184,20 @@
                 "nistp521",
                 "secp256k1"
             ],
-            "time": "2018-04-12T11:17:52+00:00"
+            "time": "2019-11-14T13:43:07+00:00"
         },
         {
             "name": "symfony/polyfill-mbstring",
-            "version": "v1.11.0",
+            "version": "v1.9.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/symfony/polyfill-mbstring.git",
-                "reference": "fe5e94c604826c35a32fa832f35bd036b6799609"
+                "reference": "d0cd638f4634c16d8df4508e847f14e9e43168b8"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/fe5e94c604826c35a32fa832f35bd036b6799609",
-                "reference": "fe5e94c604826c35a32fa832f35bd036b6799609",
+                "url": "https://api.github.com/repos/symfony/polyfill-mbstring/zipball/d0cd638f4634c16d8df4508e847f14e9e43168b8",
+                "reference": "d0cd638f4634c16d8df4508e847f14e9e43168b8",
                 "shasum": ""
             },
             "require": {
@@ -209,7 +209,7 @@
             "type": "library",
             "extra": {
                 "branch-alias": {
-                    "dev-master": "1.11-dev"
+                    "dev-master": "1.9-dev"
                 }
             },
             "autoload": {
@@ -243,26 +243,26 @@
                 "portable",
                 "shim"
             ],
-            "time": "2019-02-06T07:57:58+00:00"
+            "time": "2018-08-06T14:22:27+00:00"
         },
         {
             "name": "web3p/ethereum-util",
-            "version": "0.1.1",
+            "version": "0.1.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/web3p/ethereum-util.git",
-                "reference": "4e5ef4dc4d60f7c8939f9f4da6f8dff5d51a2e91"
+                "reference": "c7b5edd1a3ca20d0dae93f6fb9d253c61dfb73c6"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/web3p/ethereum-util/zipball/4e5ef4dc4d60f7c8939f9f4da6f8dff5d51a2e91",
-                "reference": "4e5ef4dc4d60f7c8939f9f4da6f8dff5d51a2e91",
+                "url": "https://api.github.com/repos/web3p/ethereum-util/zipball/c7b5edd1a3ca20d0dae93f6fb9d253c61dfb73c6",
+                "reference": "c7b5edd1a3ca20d0dae93f6fb9d253c61dfb73c6",
                 "shasum": ""
             },
             "require": {
                 "kornrunner/keccak": "~1",
                 "php": "^7.1",
-                "simplito/elliptic-php": "1.0.3"
+                "simplito/elliptic-php": "~1.0.6"
             },
             "require-dev": {
                 "phpunit/phpunit": "^6.1"
@@ -284,24 +284,24 @@
                 }
             ],
             "description": "A collection of utility functions for Ethereum written in PHP.",
-            "time": "2018-08-17T06:28:32+00:00"
+            "time": "2019-11-23T08:43:24+00:00"
         },
         {
             "name": "web3p/rlp",
-            "version": "0.2.2",
+            "version": "0.3.2",
             "source": {
                 "type": "git",
                 "url": "https://github.com/web3p/rlp.git",
-                "reference": "1d0ebb4cb3baf5c45d0c653aecbe3f8daffd3bcd"
+                "reference": "bc9e29f7a1f658408f25322ea21ff5687a851470"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/web3p/rlp/zipball/1d0ebb4cb3baf5c45d0c653aecbe3f8daffd3bcd",
-                "reference": "1d0ebb4cb3baf5c45d0c653aecbe3f8daffd3bcd",
+                "url": "https://api.github.com/repos/web3p/rlp/zipball/bc9e29f7a1f658408f25322ea21ff5687a851470",
+                "reference": "bc9e29f7a1f658408f25322ea21ff5687a851470",
                 "shasum": ""
             },
             "require-dev": {
-                "phpunit/phpunit": "~6.0"
+                "phpunit/phpunit": "~7"
             },
             "type": "library",
             "autoload": {
@@ -320,35 +320,33 @@
                 }
             ],
             "description": "Recursive Length Prefix Encoding in PHP.",
-            "time": "2018-06-10T09:55:27+00:00"
+            "time": "2019-11-23T08:20:30+00:00"
         }
     ],
     "packages-dev": [
         {
             "name": "doctrine/instantiator",
-            "version": "1.2.0",
+            "version": "1.1.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/doctrine/instantiator.git",
-                "reference": "a2c590166b2133a4633738648b6b064edae0814a"
+                "reference": "185b8868aa9bf7159f5f953ed5afb2d7fcdc3bda"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/doctrine/instantiator/zipball/a2c590166b2133a4633738648b6b064edae0814a",
-                "reference": "a2c590166b2133a4633738648b6b064edae0814a",
+                "url": "https://api.github.com/repos/doctrine/instantiator/zipball/185b8868aa9bf7159f5f953ed5afb2d7fcdc3bda",
+                "reference": "185b8868aa9bf7159f5f953ed5afb2d7fcdc3bda",
                 "shasum": ""
             },
             "require": {
                 "php": "^7.1"
             },
             "require-dev": {
-                "doctrine/coding-standard": "^6.0",
+                "athletic/athletic": "~0.1.8",
                 "ext-pdo": "*",
                 "ext-phar": "*",
-                "phpbench/phpbench": "^0.13",
-                "phpstan/phpstan-phpunit": "^0.11",
-                "phpstan/phpstan-shim": "^0.11",
-                "phpunit/phpunit": "^7.0"
+                "phpunit/phpunit": "^6.2.3",
+                "squizlabs/php_codesniffer": "^3.0.2"
             },
             "type": "library",
             "extra": {
@@ -373,25 +371,25 @@
                 }
             ],
             "description": "A small, lightweight utility to instantiate objects in PHP without invoking their constructors",
-            "homepage": "https://www.doctrine-project.org/projects/instantiator.html",
+            "homepage": "https://github.com/doctrine/instantiator",
             "keywords": [
                 "constructor",
                 "instantiate"
             ],
-            "time": "2019-03-17T17:37:11+00:00"
+            "time": "2017-07-22T11:58:36+00:00"
         },
         {
             "name": "myclabs/deep-copy",
-            "version": "1.9.1",
+            "version": "1.8.1",
             "source": {
                 "type": "git",
                 "url": "https://github.com/myclabs/DeepCopy.git",
-                "reference": "e6828efaba2c9b79f4499dae1d66ef8bfa7b2b72"
+                "reference": "3e01bdad3e18354c3dce54466b7fbe33a9f9f7f8"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/myclabs/DeepCopy/zipball/e6828efaba2c9b79f4499dae1d66ef8bfa7b2b72",
-                "reference": "e6828efaba2c9b79f4499dae1d66ef8bfa7b2b72",
+                "url": "https://api.github.com/repos/myclabs/DeepCopy/zipball/3e01bdad3e18354c3dce54466b7fbe33a9f9f7f8",
+                "reference": "3e01bdad3e18354c3dce54466b7fbe33a9f9f7f8",
                 "shasum": ""
             },
             "require": {
@@ -426,7 +424,7 @@
                 "object",
                 "object graph"
             ],
-            "time": "2019-04-07T13:18:21+00:00"
+            "time": "2018-06-11T23:09:50+00:00"
         },
         {
             "name": "phar-io/manifest",
@@ -586,16 +584,16 @@
         },
         {
             "name": "phpdocumentor/reflection-docblock",
-            "version": "4.3.1",
+            "version": "4.3.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/phpDocumentor/ReflectionDocBlock.git",
-                "reference": "bdd9f737ebc2a01c06ea7ff4308ec6697db9b53c"
+                "reference": "94fd0001232e47129dd3504189fa1c7225010d08"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/bdd9f737ebc2a01c06ea7ff4308ec6697db9b53c",
-                "reference": "bdd9f737ebc2a01c06ea7ff4308ec6697db9b53c",
+                "url": "https://api.github.com/repos/phpDocumentor/ReflectionDocBlock/zipball/94fd0001232e47129dd3504189fa1c7225010d08",
+                "reference": "94fd0001232e47129dd3504189fa1c7225010d08",
                 "shasum": ""
             },
             "require": {
@@ -633,7 +631,7 @@
                 }
             ],
             "description": "With this component, a library can provide support for annotations via DocBlocks or otherwise retrieve information that is embedded in a DocBlock.",
-            "time": "2019-04-30T17:48:53+00:00"
+            "time": "2017-11-30T07:14:17+00:00"
         },
         {
             "name": "phpdocumentor/type-resolver",
@@ -996,16 +994,16 @@
         },
         {
             "name": "phpunit/phpunit",
-            "version": "6.5.14",
+            "version": "6.5.11",
             "source": {
                 "type": "git",
                 "url": "https://github.com/sebastianbergmann/phpunit.git",
-                "reference": "bac23fe7ff13dbdb461481f706f0e9fe746334b7"
+                "reference": "7bab54cb366076023bbf457a2a0d513332cd40f2"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/bac23fe7ff13dbdb461481f706f0e9fe746334b7",
-                "reference": "bac23fe7ff13dbdb461481f706f0e9fe746334b7",
+                "url": "https://api.github.com/repos/sebastianbergmann/phpunit/zipball/7bab54cb366076023bbf457a2a0d513332cd40f2",
+                "reference": "7bab54cb366076023bbf457a2a0d513332cd40f2",
                 "shasum": ""
             },
             "require": {
@@ -1076,7 +1074,7 @@
                 "testing",
                 "xunit"
             ],
-            "time": "2019-02-01T05:22:47+00:00"
+            "time": "2018-08-07T07:05:35+00:00"
         },
         {
             "name": "phpunit/phpunit-mock-objects",
@@ -1697,76 +1695,18 @@
             "homepage": "https://github.com/sebastianbergmann/version",
             "time": "2016-10-03T07:35:21+00:00"
         },
-        {
-            "name": "symfony/polyfill-ctype",
-            "version": "v1.11.0",
-            "source": {
-                "type": "git",
-                "url": "https://github.com/symfony/polyfill-ctype.git",
-                "reference": "82ebae02209c21113908c229e9883c419720738a"
-            },
-            "dist": {
-                "type": "zip",
-                "url": "https://api.github.com/repos/symfony/polyfill-ctype/zipball/82ebae02209c21113908c229e9883c419720738a",
-                "reference": "82ebae02209c21113908c229e9883c419720738a",
-                "shasum": ""
-            },
-            "require": {
-                "php": ">=5.3.3"
-            },
-            "suggest": {
-                "ext-ctype": "For best performance"
-            },
-            "type": "library",
-            "extra": {
-                "branch-alias": {
-                    "dev-master": "1.11-dev"
-                }
-            },
-            "autoload": {
-                "psr-4": {
-                    "Symfony\\Polyfill\\Ctype\\": ""
-                },
-                "files": [
-                    "bootstrap.php"
-                ]
-            },
-            "notification-url": "https://packagist.org/downloads/",
-            "license": [
-                "MIT"
-            ],
-            "authors": [
-                {
-                    "name": "Symfony Community",
-                    "homepage": "https://symfony.com/contributors"
-                },
-                {
-                    "name": "Gert de Pagter",
-                    "email": "BackEndTea@gmail.com"
-                }
-            ],
-            "description": "Symfony polyfill for ctype functions",
-            "homepage": "https://symfony.com",
-            "keywords": [
-                "compatibility",
-                "ctype",
-                "polyfill",
-                "portable"
-            ],
-            "time": "2019-02-06T07:57:58+00:00"
-        },
         {
             "name": "theseer/tokenizer",
-            "version": "1.1.2",
+            "version": "1.1.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/theseer/tokenizer.git",
-                "reference": "1c42705be2b6c1de5904f8afacef5895cab44bf8"
+                "reference": "cb2f008f3f05af2893a87208fe6a6c4985483f8b"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/theseer/tokenizer/zipball/1c42705be2b6c1de5904f8afacef5895cab44bf8",
-                "reference": "1c42705be2b6c1de5904f8afacef5895cab44bf8",
+                "url": "https://api.github.com/repos/theseer/tokenizer/zipball/cb2f008f3f05af2893a87208fe6a6c4985483f8b",
+                "reference": "cb2f008f3f05af2893a87208fe6a6c4985483f8b",
                 "shasum": ""
             },
             "require": {
@@ -1793,25 +1733,24 @@
                 }
             ],
             "description": "A small library for converting tokenized PHP source code into XML and potentially other formats",
-            "time": "2019-04-04T09:56:43+00:00"
+            "time": "2017-04-07T12:08:54+00:00"
         },
         {
             "name": "webmozart/assert",
-            "version": "1.4.0",
+            "version": "1.3.0",
             "source": {
                 "type": "git",
                 "url": "https://github.com/webmozart/assert.git",
-                "reference": "83e253c8e0be5b0257b881e1827274667c5c17a9"
+                "reference": "0df1908962e7a3071564e857d86874dad1ef204a"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/webmozart/assert/zipball/83e253c8e0be5b0257b881e1827274667c5c17a9",
-                "reference": "83e253c8e0be5b0257b881e1827274667c5c17a9",
+                "url": "https://api.github.com/repos/webmozart/assert/zipball/0df1908962e7a3071564e857d86874dad1ef204a",
+                "reference": "0df1908962e7a3071564e857d86874dad1ef204a",
                 "shasum": ""
             },
             "require": {
-                "php": "^5.3.3 || ^7.0",
-                "symfony/polyfill-ctype": "^1.8"
+                "php": "^5.3.3 || ^7.0"
             },
             "require-dev": {
                 "phpunit/phpunit": "^4.6",
@@ -1844,7 +1783,7 @@
                 "check",
                 "validate"
             ],
-            "time": "2018-12-25T11:19:39+00:00"
+            "time": "2018-01-29T19:49:41+00:00"
         }
     ],
     "aliases": [],
diff --git a/src/Transaction.php b/src/Transaction.php
index 0a4ad3e..04ed8db 100644
--- a/src/Transaction.php
+++ b/src/Transaction.php
@@ -148,7 +148,7 @@ public function __construct($txData=[])
 
                 foreach ($txData as $txKey => $data) {
                     if (is_int($txKey)) {
-                        $hexData = $data->toString('hex');
+                        $hexData = $data;
 
                         if (strlen($hexData) > 0) {
                             $tx[$txKey] = '0x' . $hexData;
@@ -357,7 +357,7 @@ public function sign(string $privateKey)
         $this->offsetSet('v', $v);
         $this->privateKey = $privateKey;
 
-        return $this->serialize()->toString('hex');
+        return $this->serialize();
     }
 
     /**
@@ -396,9 +396,9 @@ public function hash($includeSignature=false)
             }
             $this->txData = $rawTxData;
         }
-        $serializedTx = $this->rlp->encode($txData)->toString('utf8');
+        $serializedTx = $this->rlp->encode($txData);
 
-        return $this->util->sha3($serializedTx);
+        return $this->util->sha3(hex2bin($serializedTx));
     }
 
     /**
diff --git a/test/unit/TransactionTest.php b/test/unit/TransactionTest.php
index 09ca49c..9dd1e79 100644
--- a/test/unit/TransactionTest.php
+++ b/test/unit/TransactionTest.php
@@ -168,12 +168,12 @@ public function testSerialize()
             'data' => '0xd46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675'
         ]);
 
-        $this->assertEquals('f84f018609184e72a0008276c094d46e8dd67c5d32be8058bb8eb970870f07244567849184e72aa9d46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675', $transaction->serialize()->toString('hex'));
+        $this->assertEquals('f84f018609184e72a0008276c094d46e8dd67c5d32be8058bb8eb970870f07244567849184e72aa9d46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675', $transaction->serialize());
 
         // sign tx
         $transaction->sign($this->testPrivateKey);
 
-        $this->assertEquals('f892018609184e72a0008276c094d46e8dd67c5d32be8058bb8eb970870f07244567849184e72aa9d46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f07244567523a0a48d3ce9c68bb49825aea5335bd07432823e858e8a504767d08290c28aafddf8a0416c7abc3a67080db0ad07c42de82db4e05518f99595119677398c68d431ab37', $transaction->serialize()->toString('hex'));
+        $this->assertEquals('f892018609184e72a0008276c094d46e8dd67c5d32be8058bb8eb970870f07244567849184e72aa9d46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f07244567523a0a48d3ce9c68bb49825aea5335bd07432823e858e8a504767d08290c28aafddf8a0416c7abc3a67080db0ad07c42de82db4e05518f99595119677398c68d431ab37', $transaction->serialize());
     }
 
     /**
@@ -197,7 +197,7 @@ public function testEIP155()
         $transaction['r'] = '';
         $transaction['s'] = '';
         $transaction['v'] = 1;
-        $this->assertEquals('ec098504a817c800825208943535353535353535353535353535353535353535880de0b6b3a764000080018080', $transaction->serialize()->toString('hex'));
+        $this->assertEquals('ec098504a817c800825208943535353535353535353535353535353535353535880de0b6b3a764000080018080', $transaction->serialize());
 
         $transaction = new Transaction([
             'nonce' => '0x09',
@@ -223,7 +223,7 @@ public function testEIP155()
         $this->assertEquals('f864098504a817c800825208943535353535353535353535353535353535353535808025a0855ec9b7d4fcabf535fe4ac4a7c31a9e521214d05bc6efbc058d4757c35e92bba0043d7df30c8a79e5522b3de8fc169df5fa7145714100ee8ec413292d97ce4d3a', $transaction->sign('0x4646464646464646464646464646464646464646464646464646464646464646'));
 
         $transaction = new Transaction('0xf86c098504a817c800825208943535353535353535353535353535353535353535880de0b6b3a76400008025a028ef61340bd939bc2195fe537567866003e1a15d3c71ff63e1590620aa636276a067cbe9d8997f761aecb703304b3800ccf555c9f3dc64214b297fb1966a3b6d83');
-        $this->assertEquals('f86c098504a817c800825208943535353535353535353535353535353535353535880de0b6b3a76400008025a028ef61340bd939bc2195fe537567866003e1a15d3c71ff63e1590620aa636276a067cbe9d8997f761aecb703304b3800ccf555c9f3dc64214b297fb1966a3b6d83', $transaction->serialize()->toString('hex'));
+        $this->assertEquals('f86c098504a817c800825208943535353535353535353535353535353535353535880de0b6b3a76400008025a028ef61340bd939bc2195fe537567866003e1a15d3c71ff63e1590620aa636276a067cbe9d8997f761aecb703304b3800ccf555c9f3dc64214b297fb1966a3b6d83', $transaction->serialize());
     }
 
     /**